Effects of melting time and temperature on the microstructure and thermoelectric properties of p-type Bi0.3Sb1.7Te3 alloy

Abstract

It has been widely acknowledged that the melting time and temperature have a significant influence on the microstructure and physical properties of alloys. Therefore, a proper melting process is one of the decisive factors for optimizing the microstructure and thermoelectric performance of materials. Herein, we prepared polycrystalline p-type Bi0.3Sb1.7Te3 alloys with the different melting time and temperature, and estimated the effects of melting history on microstructures, electrical and thermal transport properties. The results show that with the prolongation of melting time, the grain sizes are refined, leading to enhanced phonon scatterings and reduced thermal conductivity. Owing to the increased density of anti-site defects, the electrical conductivity increases and Seebeck coefficient decreases. Moreover, via raising the melting temperature, the lattice thermal conductivity is notably decreased due to an enhanced phonon scattering from the increased density of hierarchical crystal defects. Consequently, an enhanced zT, over 0.6 at 156 °C, is achieved in the bulk ingot melted at 1050 °C for 4 h.